JP2999342B2 - Path route test method in ATM transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an asynchronous transfer mode (AT).
The present invention relates to an ATM transmission system for transmitting data in a cell format using M), and more particularly to a path route test method in an ATM transmission system for easily determining the normality of a path route in the system.

[0002]

2. Description of the Related Art In a transmission system for performing data transmission using ATM cells,
The data is accommodated in a fixed-length ATM cell having a length of 53 bytes, and a virtual path identifier (VPI) and a virtual channel identifier (VCI) are added to the header thereof and input to an exchange in the transmission system. Are exchanged using the switching information corresponding to the value of, and transmission to the communication partner side is performed.

When testing the path route of such an ATM transmission system, it is necessary to determine from the outside whether or not the ATM cell sent from the subscriber side passes through the path as instructed by the software side. There was a problem that it was difficult. Further, when debugging the system, it is difficult to determine how far the cell has been transmitted and where the fault has occurred.

An object of the present invention is to provide a test method for online testing of a path route in an ATM cell transmission system which is asynchronously transferred during actual system operation.

[0005]

FIG. 1 is a block diagram showing the principle of the present invention. FIG. 1 is a block diagram showing the principle of a path route test method in an ATM transmission system in which data is transferred in a cell format in an asynchronous transfer mode.

Referring to FIG. 1, a case where a plurality of paths are established inside the ATM transmission system 1 will be described first. The valid cell detecting means 2 is a specific virtual path identifier corresponding to the path.
(VPI) and virtual channel identifier (VCI)
The valid cell , which is the cell transmitted to that location.
A valid cell is output when the cell enable signal
Thing is intended to detect the arrival of a valid cell drives out detection of showing, for example, a valid cell detector.

[0007] The VPI / VCI comparing means 3 and the path route normality checking means 4 are provided at one or more locations in the system together with the valid cell detecting means 2. Among them, the VPI / VCI comparison means 3 is a set of values of a virtual path identifier (VPI) and a virtual channel identifier (VCI) added to a cell to be transferred via a place where these means are provided. holds, is added to the value and arrived cell Tei Ru VPI and VCI held VPI
The path route normality checking means 4 detects the arrival of a valid cell by the valid cell detecting means 2 and the VPI / VCI comparing means 3
And when the VCI match is detected, the normality of the path route in the system is confirmed.

When only one path is set up in the ATM transmission system, there is no need to compare the values of VPI / VCI, and the valid cell detecting means 2 for detecting the arrival of a valid cell is replaced by one in the ATM transmission system. By providing at more than one location, the normality of the path route in the system is confirmed.

[0009]

According to the present invention, the path route test in the ATM transmission system is executed online. Generally, when a plurality of paths are set up inside a transmission system, a VPI for comparing the values of VPI and VCI is added to an effective cell detecting means 2 for detecting arrival of an effective cell at a necessary place in the system. / VCI comparing means 3 and path route normality confirming means 4, for example, a valid cell detector constituting valid cell detecting means 2 indicates transmission of valid cells.
The arrival of a valid cell is detected by the detection of the cell enable signal that is being transmitted, and the VPI and VCI added to the cell to be transferred, which are stored in a table inside the VPI / VCI comparison means 3, are added. Is matched with those added to the arrival cell, the normality of the path route to that point is confirmed.

In the present invention, for example, a test cell transmitting means for transmitting a test cell for a path route test is provided on an input line side of a transmission system, and a test cell in which a specific virtual channel identifier (VCI) value is set is used. It is also possible to confirm the normality of the path route at each point on the path route to be transmitted and passed by the test cell. Furthermore, this V
By using two test cells in which two values complementary to each other are set as CI values, it is also possible to monitor the bit stack of the path route, that is, the failure of the bit line.

As described above, according to the present invention, the normality of the path route in the system is confirmed by detecting the arrival of a valid cell and comparing it with VPI and VCI.

[0012]

FIG. 2 is a block diagram showing the overall configuration of an ATM transmission system using the path route test method of the present invention. In FIG. 1, for example, data sent from a subscriber 10 is multiplexed by a multiplexer 12 via a subscriber line device 11 and exchanged in a switch unit 13 in the form of an ATM cell. It is sent to the receiving subscriber 16 through the line device 15.

FIG. 3 is an explanatory diagram of a cell frame signal indicating the head of a cell and a cell enable signal indicating a distinction between a valid cell and an invalid cell. In the figure, the cell enable signal has a value of "L" for a valid cell and a value of "H" for an invalid cell.

FIG. 4 is a block diagram showing the configuration of a valid cell detector (VCD) for detecting the arrival of a valid cell. When only one path is provided in the transmission system of FIG. 2, a cell having a specific virtual path identifier (VPI) and a specific virtual channel identifier (VCI) corresponding to a line constituting the path is provided in the system. Only are transmitted as valid cells. Thus, the arrival of a valid cell can be detected at various points in the system through which the cell passes, for example, a subscriber line, a path in a switch unit, and an output line.

The valid cell detector shown in FIG. 4 is installed at an arbitrary position in the system. When an inverted signal of a cell enable signal is input to a clock terminal of a flip-flop 19 via an inverter 18, the valid cell detector detects the arrival of a valid cell. Is performed. That is, the cell enable signal is
As shown in (1), the signal has a 53 clock width per cell, and the clock input value becomes "H" corresponding to the valid cell, and the flip-flop 19 is set by this signal.

An LED is provided for each of the plurality of valid cell detectors, and the LEDs are turned on in response to the arrival of an effective cell, or the output of the valid cell detector is sent to the software interface unit, and the software Can be sent as one of the status data. With this configuration, the output of the valid cell detector can be displayed, and the normality of the path route can be confirmed without using another measuring device.

Generally, a plurality of paths are provided in an ATM transmission system. In this case, at any point in the system, a virtual path identifier (VPI) and a virtual channel identifier (VC) held by a cell passing through the point.
I) is provided, and the contents of the table and VPI and VC in the actually transmitted ATM cell are provided.
By comparing with I, it is possible to confirm the normality of the path route to the valid cell when it arrives.

FIG. 5 is a block diagram showing the configuration of such a path route confirmation unit. In the figure, a path route confirming unit includes a VPI / VCI table 21 holding values of VPI and VCI added to a cell passing through the location, a VP for extracting values of VPI and VCI from an arriving cell.
An I / VCI monitor 22, a comparator 23 for comparing the contents of the VPI / VCI table 21 with the extracted VPI / VCI value, a valid cell detector 24 for detecting the arrival of a valid cell, and a comparator 23 and a valid cell detector 24, and is constituted by an AND circuit 25 for outputting a result of checking the normality of the path route. The contents of the VPI / VCI table 21 are set from a host computer (not shown).

Next, in the present invention, for example, the input side line section is provided with a function of generating a test cell different from a normal data transmission cell, and a test cell having a specific VCI value is input into the system. By doing so, a test aiming at a path up to an arbitrary output side line can be performed. The value of this VCI is set in advance in the VPI / VCI table 21 in the path route confirmation unit provided at each location inside the path, and the path route is confirmed. As the value of the VCI, a value set in advance corresponding to the system may be used, or a value not currently used by the software may be selected and assigned.

Further, as the value of the VCI, two values having a complement relation to each other, for example, 5555 as one value
(HEX), AAAA can be used as the other value. This is effective when each of 53 bytes of the ATM cell, that is, 8 bits are transmitted in parallel,
Used for monitoring a bit stack, that is, a bit line failure. If there is a bit line failure, the output for a particular bit line will always be fixed to either 0 or 1 and the two VCs in a complement relationship will be fixed.
By using I, it is possible to monitor a bit line failure, that is, a bit stack.

FIG. 6 is a block diagram showing the configuration of an embodiment of a broadband ISDN system using the path route test method of the present invention. In the figure, the system includes, for example, a terminal adapter (TA1) 30 on the transmission side, terminal adapters (TA2, TA3) 36, 44 on the reception side, subscriber line interfaces (SINF) 31, 35, 43, a multi-demultiplexer (MDX). ) 32, 34, 37, 40, 4
2. Broadband remote switch unit (BRS
U) 33, fiber loop interface (FINF)
38, 39 and a central office switch 41.

In FIG. 6, for example, consider a case where data is sent from the terminal adapter (TA1) 30 side. In the case where only one path is established on the input side of each device in the system, or only one path is established in FIG. Is provided with a valid cell detector for detecting the arrival of a valid cell.

Consider now the case where only the path from the terminal adapter 30 to the terminal adapter 36 is established.
Of the VCDs in the system, the results of VCD determinations at each of a, b, c, k, and l should indicate arrival of a valid cell,
Similarly, if only the path to the terminal adapter 44 is established, the VCDs at a, b, c, d, e, f, g, h, i, and j should detect the arrival of a valid cell. .

In the former case, if the VCDs of k and l do not detect the arrival of a valid cell, there is a possibility that the switch 33 has a failure or that the MDX 32 does not provide accurate switching information.
Therefore, it is sufficient to investigate these two points. If there is no such function, there is no method of isolating a fault other than sequentially measuring input / output data of each device using an oscilloscope or a logic analyzer.

Also, as a practical matter, since the terminal adapter is often remote from the system, a test cell generator is provided inside the subscriber line interface (SINF) or the fiber loop interface (FINF), and the test is performed from here. By generating cells, it is also possible to test a path in a small area.

For example, by generating a test cell from the FINF 38, it is possible to perform a test only for the central office. The central office here is F
It includes the parts from INF39 to SINF43.
Further, by generating test cells from both the FINF 38 and the SINF 43 at the same time, it is possible to determine whether the fault is in the direction from BRSU to CO or the fault in the direction from CO to BRSU. Here, the broadband remote station provided with the BRSU includes portions from SINF31 to FINF35 and 38.

[0027]

As described above in detail, according to the present invention, the normality of the path route and the monitoring of the bit stack can be performed on-line without using a measuring instrument. It is possible to find a faulty part at an early stage, which greatly contributes to improving the reliability of the system and facilitating maintenance.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a block diagram showing an overall configuration of an ATM transmission system using the path route test method of the present invention.

FIG. 3 is a diagram illustrating a cell frame signal and a cell enable signal.

FIG. 4 is a block diagram illustrating a configuration of a valid cell detector.

FIG. 5 is a block diagram illustrating a configuration of a path route confirmation unit.

FIG. 6 is a block diagram illustrating a configuration of an embodiment of a wide band ISDN transmission system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ATM transmission system 2 Effective cell detection means 3 VPI / VCI comparison means 4 Path route normality confirmation means 21 VPI / VCI table 22 VPI / VCI monitor 23 Comparator 24 Valid cell detector 25 AND circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-369945 (JP, A) JP-A-2-218239 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/28

Claims (4)

(57) [Claims] An ATM transmission system for performing data transfer in a cell format in an asynchronous transfer mode (ATM), wherein when only one path is established in the ATM transmission system (1), one or more of the paths in the system are provided. point, the pair to the path of
Specific virtual path identifier (VPI) and virtual channel
With a channel identifier (VCI).
Effective cell detecting means (2) for detecting the arrival of a valid cell by detecting that a cell enable signal indicating the transmission of a valid cell as a valid cell has been transmitted. A path route test method in an ATM transmission system, wherein the normality of a path route in the system is confirmed by the arrival of the valid cell. 2. When a plurality of paths are established in the ATM transmission system (1), at one or more points in the system, in addition to the effective cell detecting means (2), via the points. Holding a set of values of a virtual path identifier (VPI) and a virtual channel identifier (VCI) added to the cell to be transmitted as the
And the VPI and VC added to the arriving cell
VPI / VCI comparing means for comparing with the value of I (3)
The valid cell detecting means (2) detects arrival of a valid cell, and the VPI / VCI comparing means (3) outputs VPI and VC
2. A path route test method in an ATM transmission system according to claim 1, further comprising path route normality checking means for checking the normality of the path route in the system when a match of I is detected. 3. An ATM transmission system according to claim 1, further comprising: a test cell transmitting means for transmitting a test cell for a path route test at an arbitrary position in the ATM transmission system; The valid cell detecting means (2), VPI / VCI comparing means (3), and path route normality checking means (4)
3. The path route test method in an ATM transmission system according to claim 2, wherein the normality of the path route in the system can be confirmed using a test cell. 4. Two test cells in which data are transmitted in 8-bit parallel in the ATM transmission system (1), and two values which are complementary to each other are set as the virtual channel identifier (VCI). 4. The path route test method in an ATM transmission system according to claim 3, wherein the bit stack of the path route in the system can be monitored using the bit stack.